A camper is trying to start a fire by focusing sunlight onto a piece of paper. The diameter of the sun is 1.39e9 m, and its mean distance from the earth is 1.50e11 m. The camper is using a converging lens whose focal length is 10.8 cm.
(a) What is the area of the sun's image on the paper?
(b) If 0.568 W of sunlight passes through the lens, what is the intensity of the sunlight at the paper?
(a) A=.25*pi*(height of sun's image)^2 and m=-di/do
The Attempt at a Solution
B should not be an issue if I can find A. I do not know how to find the height of the sun's image.